Canidae

Canids[1]
Fossil range: 39.75–0 Ma
Late Eocene - Recent
Various canid species: Arctic fox (top left), Red fox (top right), Grey wolf (bottom left) and coyote (bottom right)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Suborder: Caniformia
Family: Canidae
G. Fischer de Waldheim, 1817
Genera and species

See text

Canidae (pronounced /ˈkænɨdiː/[2]) is the biological family of carnivorous and omnivorous mammals that includes the wolves, foxes, jackals, coyotes, and the domestic dog; a member of this family is called a canid (/ˈkeɪnɨd/). The Canidae family is divided into the "wolf-like" and "dog-like" animals of the tribe Canini and the "foxes" of the tribe Vulpini. The two species of the basal Caninae are more primitive and do not fit into either tribe.

Contents

Classification and relationship

The subdivision of Canidae into "foxes" and "true dogs" may not be in accordance with the actual relations; also the taxonomic classification of several canines is disputed. Recent DNA analysis shows that Canini (dogs) and Vulpini (foxes) are valid clades. (See phylogeny below). Molecular data implies a North American origin of living Canidae and an African origin of wolf-like canines (Canis, Cuon, and Lycaon).[3]

Currently, the domestic dog is listed as a subspecies of Canis lupus, C. l. familiaris, and the Dingo (also considered a domestic dog) as C. l. dingo, provisionally a separate subspecies from C. l. familiaris; the Red Wolf, Eastern Canadian Wolf, and Indian Wolf are recognized as subspecies.[1] Many sources list the domestic dog as Canis familiaris, but others, including the Smithsonian Institution and the American Society of Mammalogists, more precisely list it as a subspecies of C. l. familiaris; the Red Wolf, Eastern Canadian Wolf, and Indian Wolf may or may not be separate species; the Dingo has been in the past variously classified as Canis dingo, Canis familiaris dingo and Canis lupus familiaris dingo.

Evolution

Eocene epoch

Carnivorans evolved from miacoids about 55 million years ago during the late Paleocene.[4] Then, about 50 million years ago, the carnivorans split into two main divisions: caniforms (dog-like) and feliforms (cat-like). By 40 million years ago the first clearly identifiable member of the dog family Canidae had arisen. It was called Prohesperocyon wilsoni and was found in what is now southwestern Texas. This fossil species bears a combination of features that definitively mark it as a canid: teeth that include the loss of the upper third molar (a general trend toward a more shearing bite), and the characteristically enlarged bony bulla (the rounded covering over the middle ear). Based on what we know about its descendants, Prohesperocyon likely had slightly more elongated limbs than its predecessors, along with toes that were parallel and closely touching, rather than splayed, as in bears.[5]

The Canidae family soon subdivided into three subfamilies, each of which diverged during the Eocene: Hesperocyoninae (~39.74-15 Mya), Borophaginae (~36-2 Mya), and the Caninae lineage that led to present-day canids (wolves, foxes, coyotes, jackals, and domestic dogs). Each of these groups showed an increase in body mass with time, and sometimes exhibited a specialised hypercarnivorous diet that made them prone to extinction.[6]:Fig. 1 Only the Caninae lineage, commonly referred to as "canines", survived to the present day.

Oligocene epoch

The earliest branch of the Canidae was the Hesperocyoninae lineage, which included the coyote-sized Mesocyon of the Oligocene (38-24 Mya). These early canids probably evolved for fast pursuit of prey in a grassland habitat, and resembled modern civets in appearance. Hesperocyonines became extinct except for the Nothocyon and Leptocyon branches. These branches led to the borophagine and canine radiations.[7]

Miocene epoch

Around 9-10 Mya during the Late Miocene, Canis, Urocyon, and Vulpes genera expanded from southwestern North America. This was the point where the canine radiation began. The success of these canines was related to the development of lower carnassials that were capable of both mastication and shearing. Around 8 Mya, Beringia offered the canines a way to enter Eurasia.

Pliocene epoch

During the Pliocene around (4-5 Mya) Canis lepophagus appeared in North America. This was small and sometimes coyote-like. Others were wolf-like in characteristics. It is theorized that Canis latrans (the coyote) descended from Canis lepophagus.[8]

The formation of the Isthmus of Panama about 3 Mya joined South America to North America, allowing canids to invade the former, where they diversified.

Pleistocene epoch

Around 1.5 to 1.8 Mya, a variety of wolves were present in Europe. Also, the North American wolf line appeared with Canis edwardii, clearly identifiable as a wolf. Canis rufus appeared, possibly a direct descendent of Canis edwardii. Around 0.8 Mya, Canis ambrusteri emerged in North America. A large wolf, it was found all over the continent. It is thought that this species migrated to South America where it became the ancestor of Canis dirus, the dire wolf.

At 0.3 Mya Canis lupus (the gray wolf) was fully developed and had spread throughout Europe and northern Asia. Berengia offered a way to North America.[9] At around 100,000 years ago, the dire wolf, one of the largest members of the dog family, had spread from South America to southern Canada and from coast to coast. The dire wolf shared its habitat with the gray wolf. Around 8,000 years ago the dire wolf became extinct.

Characteristics

Wild canids are found on every continent except Antarctica, and inhabit a wide range of different habitats, including deserts, mountains, forests, and grassland. They vary in size from the Fennec Fox at 24 cm (9.4 in) long, to the Gray Wolf, which may be up to 2 m (6.6 ft) long, and can weigh up to 80 kg (180 lb).

With the exceptions of the Bush Dog, Raccoon Dog and some domestic breeds, canids have relatively long legs and lithe bodies, adapted for chasing prey. All canids are digitigrade, meaning that they walk on their toes. They possess bushy tails, non-retractile claws, and, excepting the African Wild Dog (Lycaon pictus), a dewclaw on the front feet. They possess a baculum, which together with a cavernous body helps to create a copulatory tie during mating, locking the animals together for up to an hour. Young canids are born blind, with their eyes opening a few weeks after birth.[10]

Gray wolf pack hunting an American bison in Yellowstone National Park.

Social behavior

Almost all canids are social animals and live together in groups. In most foxes and in many of the true dogs, a male and female pair work together to hunt and to raise their young. Gray wolves and some of the other larger canids live in larger groups called packs. African wild dogs have the largest packs, which can number as many as 90 animals. Some species form packs or live in small family groups depending on the circumstances, including the type of available food. In most species, there are also some individuals who live on their own. Within a canid pack, there is a system of dominance so that the strongest, most experienced animals lead the pack. In most cases, the dominant male and female are the only pack members to breed.

Canids communicate with each other by scent signals, by visual clues and gestures, and by vocalizations such as growls, barks, and howls. In most cases, groups have a home territory from which they drive out others. The territory is marked by leaving urine scent marks, which warn trespassing individuals.[11]

Most canids bear young once a year, from 1 to 16 or more (in the case of the African wild dog) at a time. The young are born small and helpless and require a long period of care. They are kept in a den, most often dug into the ground, for warmth and protection. When they begin eating solid food, both parents, and often other pack members, bring food back for them from the hunt. This is most often vomited up from the adult's stomach. Young canids may take a year to mature and learn the skills they need to survive.[12]

Dentition

Italian wolf skull

Most canids have 42 teeth, with a dental formula of: Upper: 3.1.4.2, lower: 3.1.4.3. As in other members of Carnivora, the upper fourth premolar and lower first molar are adapted as carnassial teeth for slicing flesh. The molar teeth are strong in most species, allowing the animals to crack open bone to reach the marrow. The deciduous or baby teeth formula in canids is 3 1 3; molars are completely absent.

Species and taxonomy

Coyote
African Hunting Dog
Red Wolf
Dhole
Golden Jackal
Bat-eared Fox
Gray Fox
Maned Wolf
Short-eared Dog
Pampas Fox
Arctic Fox
Raccoon Dog
A modern domesticated West Highland White Terrier

FAMILY CANIDAE

Subfamily Caninae

Fluctuation of species within Canidae over 40 million years

Prehistoric Canidae

Classification of Hesperocyoninae from Wang (1994)[13] and Borophaginae from Wang et al. (1999),[14] except where noted.

Caninae

Borophaginae

† (Ma = million years ago) (million years = in existence)

Hesperocyoninae

† (Ma = million years ago)

Canids and humans

Traditional English fox hunt

One canid, the domestic dog, long ago entered into a partnership with humans and today remains one of the most widely kept domestic animals in the world and serves humanity in a great many important ways. Most experts believe the domestic dog is descended from an Asian subspecies of the Gray Wolf.

Among canids, only the gray wolf has been known to prey on humans.[18] There are at least two records of coyotes killing humans,[19] and two of golden jackals killing children.[20] Some canid species have also been trapped and hunted for their fur and, especially the Gray Wolf and the Red Fox, for sport. Some canids are now endangered in the wild due to hunting, habitat loss, and the introduction of diseases from domestic dogs.[21]

See also

References

  1. ↑ 1.0 1.1 Wozencraft, W. Christopher (16 November 2005). "Order Carnivora (pp. 532-628)". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=14000691. 
  2. ↑ Canidae. Dictionary.com. The American Heritage Stedman's Medical Dictionary. Houghton Mifflin Company. http://dictionary.reference.com/browse/Canidae (accessed: February 16, 2009).
  3. ↑ Lindblad-toh, K.; Wade, CM; Mikkelsen, TS; Karlsson, EK; Jaffe, DB; Kamal, M; Clamp, M; Chang, JL et al. (2005). "Genome sequence, comparative analysis and haplotype structure of the domestic dog" (PDF). Nature 438 (7069): 803–819. doi:10.1038/nature04338. PMID 16341006. http://ccr.cancer.gov/resources/cop/nature04338.pdf. Retrieved 2008-04-27. 
  4. ↑ [1]
  5. ↑ Wang, Xiaoming (2008). "How Dogs Came to Run the World". Natural History Magazine July/August. http://www.naturalhistorymag.com/master.html?http://www.naturalhistorymag.com/0708/0708_feature.html. Retrieved 2008-11-28. 
  6. ↑ doi:10.1126/science.1102417
    This citation will be automatically completed in the next few minutes. You can jump the queue or expand by hand
  7. ↑ Martin, L.D. 1989. Fossil history of the terrestrial carnivora. Pages 536 - 568 in J.L. Gittleman, editor. Carnivore Behavior, Ecology, and Evolution, Vol. 1. Comstock Publishing Associates: Ithaca.
  8. ↑ Nowak, R.M. 1979. North American Quaternary Canis. Monograph of the Museum of Natural History, University of Kansas 6:1 - 154.
  9. ↑ Nowak, R. 1992. Wolves: The great travelers of evolution. International Wolf 2(4):3 - 7.
  10. ↑ Macdonald, D. (1984). The Encyclopedia of Mammals. New York: Facts on File. pp. 57. ISBN 0-87196-871-1. 
  11. ↑ Nowak, R. M., and J. L. Paradiso. 1983. Walker's Mammals of the World. Baltimore, Maryland: The Johns Hopkins University Press. ISBN 0801825253.
  12. ↑ Voelker, W. 1986. The Natural History of Living Mammals. Medford, New Jersey: Plexus Publishing. ISBN 0937548081
  13. ↑ Wang, Xiaoming (1994). "Phylogenetic systematics of the Hesperocyoninae". Bulletin of the American Museum of Natural History 221: 1–207. http://hdl.handle.net/2246/829. 
  14. ↑ Wang, Xiaoming; Wideman, Benjamin C.; Nichols, Ralph; Hanneman, Debra L. (1999). "Phylogenetic systematics of the Borophaginae". Bulletin of the American Museum of Natural History 243: 1–391. doi:10.1671/2493. http://hdl.handle.net/2246/1588. 
  15. ↑ 15.0 15.1 Hayes, F.G. (2000). "The Brooksville 2 local fauna (Arikareean, latest Oligocene) Hernando County, Florida". Bulletin of the Florida Museum of Natural History 43 (1): 1–47. 
  16. ↑ Wang, Xiaoming; Wideman, Benjamin C.; Nichols, Ralph; Hanneman, Debra L. (2004). "A new species of Aelurodon (Carnivora, Canidae) from the Barstovian of Montana" (PDF). Journal of Vertebrate Paleontology 24 (2): 445–452. doi:10.1671/2493. http://www.nhm.org/expeditions/rrc/wang/documents/Wangetal2004MontanaAelurodon.pdf. Retrieved 2007-07-08. 
  17. ↑ Wang, Xiaoming (2003). "New Material of Osbornodon from the Early Hemingfordian of Nebraska and Florida" (PDF). Bulletin of the American Museum of Natural History 279: 163–176. http://digitallibrary.amnh.org/dspace/bitstream/2246/447/19/B279a08.pdf. 
  18. ↑ Kruuk, H. 2002. Hunter and Hunted: Relationships between Carnivores and People. Cambridge, UK: Cambridge University Press. ISBN 0521814103.
  19. ↑ "Coyote Attacks: An Increasing Suburban Problem". http://www.co.san-diego.ca.us/awm/docs/coyoteattacks.pdf. Retrieved 2007-08-19. 
  20. ↑ "Canis aureus". Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Canis_aureus.html. Retrieved 2007-07-31. 
  21. ↑ ICUN Red List

General references

Xiaoming Wang, Richard H. Tedford, Mauricio Antón, Dogs: Their Fossil Relatives and Evolutionary History, New York : Columbia University Press, 2008; ISBN 978-0-231-13528-3

External links